Solvent-Induced Chirality Inversion in Propeller-Shaped PDI Oligomers with Bright Circularly Polarized Luminescence

Abstract

Circularly polarized luminescence (CPL) has the potential for next-generation optoelectronic applications. One of the major challenges in this field is the development of CPL emitters whose emission properties can be modulated by external stimuli, such as solvents. However, CPL-active materials are often synthetically demanding and typically require chiral separation. To address these limitations, we have synthesized a propeller-shaped molecule, (R/S)-Bz-6PDI 1, via a one-pot nucleophilic aromatic substitution reaction, using a chiral pyrrole-fused perylene diimide (PDI) 4 as the blade. The introduction of a chiral auxiliary into the blade enabled the induction of propeller chirality without the need for chiral chromatographic separation. (R)-Bz-6PDI 1 exhibited high CPL brightness in solution (BCPL = 103–369 M–1cm–1). Furthermore, the propeller chirality proved highly sensitive to the solvent environment, leading to significant modulation of both the sign and intensity of the CD and CPL signals, including complete signal inversion in CH2Cl2 and CHCl3. CD spectral analysis combined with DFT calculations revealed that the propeller chirality is governed by the orientation of the hydrogen atom in the chiral auxiliary.